Fuel pump assembly

ABSTRACT

A fuel pump assembly has a pump mounted to an electric motor by a spring clamp device preferably having a plurality of arms spaced circumferentially around the pump and extending axially generally parallel to an axis of rotation of the motor, from a common base member. The base member is preferably received by the motor, and each arm preferably has a clip which projects radially inward to contact an outboard end face of the pump. The clips are preferably disengageable from the pump and exert a controlled force on the pump, thus producing a consistent and controlled clamping force across the housing encasement to eliminate any potential distortion of the preferably plastic housing.

FIELD OF THE INVENTION

The present invention relates generally to a fuel pump assembly and moreparticularly to a spring clamp device for securing a motor to a pump ofthe assembly.

BACKGROUND OF THE INVENTION

Prior art automotive fuel pump assemblies typically have an electricmotor with a stator and an armature with a drive shaft connected to afuel pump between inlet and outlet end caps which are all receivedinside of a metallic sleeve extending axially along the entire length ofthe assembly. The ends of the sleeve are rolled over and projectradially inward of the end caps to generally align and hold the assemblytogether and prevent de-coupling of the pump from the motor. Duringmanufacturing, the various components of the pump and motor and the endcaps are all assembled inside the sleeve and then both of its ends arerolled over the end caps thus securing all of the components of the pumpand motor together in axial alignment.

Unfortunately, this process requires the entire assembly be purchasedfrom a single manufacturer who assembles and/or produces both pump andmotor components. Furthermore, rolling the ends of the sleeve places acompressive force on the internal components which is not easilycontrolled or consistently repeated. Excessive stress placed upon theplastic components of the pump can degrade pump performance. Yetfurther, the sleeve-type of pump and motor assembly is expensive tomanufacture and can not be repaired without destroying the sleeve.

SUMMARY OF THE INVENTION

A fuel pump assembly has a pump coupled to an electric motor by a springclamp device preferably having a plurality of arms spacedcircumferentially around the pump and motor and extending generallyaxially and parallel to an axis of rotation of the motor, from a commonfirst member and to a plurality of second members. The first memberspans radially and is preferably received by the motor, and theplurality of second members preferably project radially inward from therespective arms to contact an outboard face of the pump. The secondmembers are preferably disengageable clips which exert a controlledforce upon the pump, thus exhibiting a consistent and controlled stressacross the pump encasement to eliminate any potential distortion of thepreferably plastic encasement.

Objects, feature, and advantages of this invention include a fuel pumpassembly which can be dis-assembled without destroying any of theassembly components, the motor and pump can be separately manufacturedand pre-assembled, and the pump encasement can be made of relativelyinexpensive plastic without concern of distortion. Operation reliabilityand performance is improved, and the assembly is rugged, durable,maintenance free, of relatively simple design, inexpensive tomanufacture and assemble, and in service has a long useful life.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other objects, features and advantages of this invention willbe apparent from the following detailed description of the presentlypreferred embodiments and best mode, appended claims, and accompanyingdrawings in which:

FIG. 1 is a side view of a fuel pump assembly of the present invention;

FIG. 2 is a bottom end view of the fuel pump assembly;

FIG. 3 is a segmented cross section of a fuel pump and spring clampdevice of the fuel pump assembly taken along line 3-3 of FIG. 2;

FIG. 4 is a cross section of the fuel pump assembly illustrating twofasteners and taken along line 4-4 of FIG. 2;

FIG. 5 is a top view of the spring clamp assembly;

FIG. 6 is a side view of the spring clamp assembly;

FIG. 7 is an enlarged fragmentary side view of the spring clamp assemblyof FIG. 6;

FIG. 8 is a side view of a second embodiment of a fuel pump assembly;

FIG. 9 is a side view of a second embodiment of the spring clamp deviceutilized in FIG. 8; and

FIG. 10 is a segmented cross section of a third embodiment of a fuelpump assembly.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring in more detail to the drawings, FIGS. 1-4 illustrate anelectric fuel pump assembly 20 embodying the present invention andhaving an electric motor 22 coupled to a fuel pump 24 secured by aspring clamp device 26 to the motor. The motor 22 is generally elongateaxially and has a stator encircling an armature with a drive shaft 34journaled for rotation by bearings carried by end caps 28 and 30received in a housing shell 32. The drive shaft 34 projects axiallyoutward from the inboard end cap or surface 30 along an axis of rotation36 for mechanical coupling to the fuel pump 24. The motor 22 and thepump 24 are preferably pre-assembled, “off-the-shelf,” items which arereleasably mounted together in coaxial alignment by the snap fittingspring clamp device 26.

Referring to FIGS. 3 and 4, the fuel pump 24 has an encasement orhousing 38 with a base 48 and a cover or end cap 52 preferably made ofnon-corrosive and economical plastic which defines a cavity 40 receivinga gear-rotor assembly 42 of a positive displacement pump. The base 48has an inboard face 44 which faces the inboard end cap or surface 30 ofthe motor 22 and a through bore 50 for receipt of the motor shaft 34.The pump end cap or cover 52 is attached and sealed to the base 48during assembly and after the gear-rotor assembly 42 is installedtherein. The end cap 52 has an outboard end face 46 and an axiallyprojecting fuel outlet 54 and a fuel inlet 56. Inlet 56 communicateswith the fuel inlet of the gear-rotor assembly 42 and outlet 54communicates with the cavity or outlet 40 of the gear-rotor assemblythrough which it discharges fuel at a high pressure when operating. Ifdesired, a turbine pump assembly or other type of fuel pump assembly maybe utilized in lieu of the gear-rotor pump assembly 42.

Referring to FIGS. 5-7, the spring clamp device 26 releasably mounts andattaches together the motor 22 and pump 24 of the fuel pump assembly 20.The clamp device 26 preferably attaches to the inboard end cap orsurface 30 of the motor 22 by two fasteners or screws 60 and extendsradially outward and axially along the pump housing 38 to partiallyenvelope or “cage,” and resiliently engage the pump 24. An annularmember or base plate 62 of the spring clamp device 26 has twodiametrically opposed holes 64 to receive the screws 60 which threadinto the end cap 30 of the motor 22 and hold the base plate 62 directlyagainst the end cap 30 in a substantially perpendicular orientation tothe axis of rotation 36. Four resilient flex arms 68 projectsubstantially axially downward from a peripheral edge 66 of the baseplate 62 and are preferably integral and unitary with the base plate.The arms 68 are preferably substantially equally spacedcircumferentially from one another and are preferably slightly bowedoutward when not flexed for engagement to the pump 24. Located at thedistal end 70 of each arm 68 is a finger or clip 72, which projectsgenerally radially inward, and resiliently snaps over the outboard face46 of the pump encasement 38 as the arms 68 resiliently flex from aradially outward unstressed state and in a generally radially inwarddirection toward a radial unstressed state and axial stressed state.

Each clip 72 has a contact portion 74 which projects radially inwardfrom its associated flex arm 68 and preferably angles axially inward atan angle 78 preferably about five degrees when in a disengaged state (asbest shown in FIGS. 6 and 7) and with respect to an imaginary plane 76disposed perpendicular to the axis of rotation 36. From the contactportion 74, the clip 72 has a rounded cam-like return bend 80 whichextends to a generally axially outward projecting distal tab 82 of theclip 72. The spring clamp device 26 is preferably made from a singlestamping of sheet metal or spring steel.

During assembly of the fuel pump assembly 20, a downward projectingcylindrical shoulder 84 of the motor housing 32, disposed concentricallyabout the shaft 34, is received in the base plate 62 of the spring clampdevice 26 through a central hole 86 (as best shown in FIG. 5). Thescrews 60 are then threaded into the motor end cap 30 which rigidlyholds the base plate 62 to the motor 22 with the flex arms 68 projectinggenerally axially away from the motor 22 (as best shown in FIGS. 3 and4). The clips 72 of the flex arms 68 are then resiliently moved radiallyoutward so that the clips 72 radially clear the pump housing 38 when thepump 24 is moved between them, and axially toward and coupled with themotor 22.

With the pump 24 coupled to the motor drive shaft 34 and the flex arms68 released, the cam-like bends 80 of the clips 72 are preferably inbiased contact with a slightly rounded peripheral edge 81 of the pumpencasement 38 but not yet in direct contact with the outboard face 46.An external force applied in a radially inward direction against themid-section of each bowed flex arm 68 causes the flex arms to generallystraighten and the contact portions 74 of the clips 72 to align parallelwith the imaginary plane 76 (as best shown in FIG. 7). The cam-like bend80 then assists each clip 72 to snap over the edge 81 and slide over theoutboard face 46 in a radially inward direction. When the external forceplaced upon the flex arms is released, the resilience or spring force ofthe bowed flex arms 68 and clips 72 exert an evenly distributed andconsistent force upon the plastic pump encasement 38 in an axiallyinward direction. If removing the pump 24 from the motor 22 is desired,a radially outward force is placed upon the clip tabs 82 which flexesthe arms 68 radially outward to radially clear the clips 72 from thecylindrical pump housing 38. Once cleared, the pump 24 can then be movedaxially away and de-coupled and removed from the motor 22.

FIGS. 8 and 9 illustrate a modified spring clamp device 26′ wherein theflex arms 68′ extend the entire axial length of the pump 24′ and motor22′ and the base plate 62′ is in biased contact with the outboard endcap 28′ of the motor housing 32′. Preferably the end cap 28′ has acylindrical shoulder 88 over which the base plate 62′ is received. Withthis modification, separate fasteners or screws are not required.

Skilled persons will understand that the orientation of the spring clampdevice 26″ relative to the motor 22″ and pump 24″ could be reversed sothat the clips 72″ engage the motor end cap or surface 28″ and the baseplate 62″ is attached to the pump base 48″ or overlies and engages tothe pump end cap 52″ (as best shown in FIG. 10).

While the forms of the invention herein disclosed constitute presentlypreferred embodiments, many others are possible. It is not intendedherein to mention all the possibly equivalent forms or ramifications ofthe invention and it is understood that the terms used herein are merelydescriptive rather than limiting and that various changes may be madewithout departing from the spirit or scope of the invention.

1. An electric motor pump assembly comprising: a pump; a separateelectric motor coupled to the pump along an axis of rotation; and aspring clamp device having; a base member carried by one of the pump andthe motor; at least two flex arms each carried by the base member andcircumferentially spaced apart and extending axially along at least oneportion of the pump and motor; and a clip projecting radially inwardfrom each flex arm adjacent a distal end of the flex arm and received bythe other of the pump and motor.
 2. The pump assembly set forth in claim1 comprising: an inboard end cap of the motor axially facing the pump;and at least one fastener engaging the base member to the inboard endcap.
 3. The pump assembly set forth in claim 2 wherein the base memberis substantially disposed axially between the pump and motor.
 4. Thepump assembly set forth in claim 3 wherein the at least one fastenerthreads into the inboard end cap.
 5. The pump assembly set forth inclaim 1 wherein the flex arm is bowed radially outward when the springclamp device is in a disengaged state.
 6. The pump assembly set forth inclaim 1 comprising a contact portion of the clip projecting radiallyinward from the flex arm and projecting slightly axially inward withrespect to the axis of rotation when the spring clamp device is in adisengaged state, and the contact portion being biased directly againstthe other of the pump and motor when the spring clamp device is in anengaged state by the flex arm.
 7. The pump assembly set forth in claim 6comprising a distal tab projecting substantially axially outward fromthe contact portion for moving the clip radially outward against theradially inward biasing force of the flex arm to release the springclamp device from the other of the pump and motor.
 8. The pump assemblyset forth in claim 1 wherein the at least two flex arms are equallyspaced circumferentially about the motor and pump and are each bowedradially outward.
 9. The pump assembly set forth in claim 8 comprising acontact portion of the clip projecting radially inward from each one ofthe plurality of flex arms and projecting slightly axially inward withrespect to the axis of rotation when the spring clamp device is in thedisengaged state, and the contact portion being biased directly againstthe other of the pump and motor when the spring clamp device is in anengaged state by the respective plurality of flex arms.
 10. The pumpassembly set forth in claim 9 comprising a distal tab projectingsubstantially axially outward from the contact portion of the clip formoving the clip radially outward against the radially inward biasingforce of each one of the at least two flex arms to release the springclamp device from the other of the pump and motor.
 11. The pump assemblyset forth in claim 1 comprising: an inboard end cap of the motor axiallyfacing the pump; an opposite outboard end cap of the motor; an outboardface of the pump facing axially from the motor; and the base memberbeing in biased contact with the outboard end cap when the clips are inbiased contact with the outboard face.
 12. The pump assembly set forthin claim 11 wherein the base member is planar and annular in shape. 13.A spring clamp device for preventing de-coupling of a pump from a motorof a pump sub-assembly and along an axis of rotation, the spring clampdevice having: a base member spanning radially with respect to the axisof rotation; a plurality of arms projecting axially from the firstmember and spaced circumferentially from one-another about the pumpsub-assembly; and a clip projecting radially with respect to the axis ofrotation and from a distal end of each one of the plurality of arms. 14.The spring clamp device set forth in claim 13 comprising an engagedstate wherein the base member and the clips are biased axially away fromone-another by at least a portion of the pump sub-assembly.
 15. Thespring clamp device set forth in claim 14 comprising: a disengaged statewherein each one of the plurality of arms are bowed radially outwardwith respect to the axis of rotation; and the engaged state causing eachone of the plurality of arms to be less bowed than when in thedisengaged state.
 16. The spring clamp device set forth in claim 14comprising: the base member being in contact with an outboard surfacecarried by the pump sub-assembly; the clips being in biased contact withan opposite outboard face carried by the pump sub-assembly; and whereinthe pump sub-assembly extends axially between the outboard surface andthe outboard face.
 17. The spring clamp device set forth in claim 13comprising: the base member being in contact with an outboard surfacecarried by the motor; the clips being in biased contact with an outboardface carried by the pump; and wherein the outboard surface faces axiallyaway from to the outboard face.
 18. The spring clamp device set forth inclaim 13 comprising: the base member being engaged to the motor via atleast one fastener; and the clips being in biased contact with anoutboard face carried by the pump.
 19. The spring clamp device set forthin claim 13 wherein the base member, the plurality of arms and the clipsare unitarily formed together from a single stamping of metal.